The present invention relates to a solar cell module and manufacturing method thereof and, more specifically, to a solar cell module used for solar electricity generation and manufacturing method thereof.
Recently, new energy has been attracting attention in view of environmental problems such as CO2 increase and exhaustion of natural resources, and, among others, solar electricity generation has been considered promising. A solar cell module as the main component thereof includes crystal based modules and thin film based modules.
The crystal based solar cell module is formed by arranging twenty to thirty crystal plates (wafers) of small area on a glass plate (cover glass) of which size corresponds to the size of the module, which are interconnected to each other, and sealed and protected by a filler such as EVA (ethylenevinyl acetate copolymer) and a back surface protective film such as Tedlar (registered trademark).
In a thin film based solar cell module (solar cell module formed on a substrate), a transparent electrode layer, a thin film semiconductor layer and a back electrode layer are directly formed on a glass plate of the size of the module successively, respective layers are separated by patterning means such as laser scribe, and connected so that desired voltage and current are obtained. As to sealing and protection, filler and surface protective film similar to those used for the crystal based solar cell module are used. The thin film based solar cell module structured as described above is advantageous in view of cost as compared with the crystal based solar cell module, in that the layer contributing to electricity generation is thin, that only one structural material is necessary, and that interconnection is simple.
As to the recent state of installment of the solar cell modules, it is not often the case that a large number of solar cell modules are used placed side by side at a remote site for solar electricity generation, and in most cases, the modules are installed on a roof of a house or installed as roof integrated type solar cell modules which also function as the house roof. Further, in these days, a so called grid connection system comes to be widely popular in which the solar cell module is installed on the roof to generate power to be consumed by the house and to sell surplus power to an electric power company, and therefore solar electricity generation systems developed for detached houses have been increasing. Such systems are developed on the premise that the solar cell module is installed on the roof of the house, and therefore appearance of the building itself and coordination with other houses therearound are of importance. In such an environment, when the surface of the solar cell module is like a mirror reflecting sun light, neighbors and passers-by may make complaints about xe2x80x9cglarexe2x80x9d and xe2x80x9cglittering.xe2x80x9d Further, architects have pointed out the problem that when the module is used as the roof material, scenery and sky are reflected on the surface of the module, impairing stylish appearance of the building.
The following measures have been devised for these problems.
For example, for a crystal based solar cell module, use of a figured glass as the cover glass has been proposed to cause random reflection and diffusion of light at the surface of the cover glass. In fact, figured glass used as the cover glass solely for this purpose is commercially available from AFG Industries Inc. of the United States, under the trade names of xe2x80x9cSunadexxe2x80x9d, xe2x80x9cSolitexe2x80x9d and xe2x80x9cSolatexxe2x80x9d. Further, it is disclosed by General Electric Company in the 16th IEEE Photovoltaic Specialists Conference, 1982 (proceedings pp. 828-833) that those figured glasses were utilized for roof tile solar cell modules.
For the thin film based solar cell modules, sealing of sub modules small in area by the structure similar to that of the crystal based solar cell modules and use of the above described dedicated figured glass as the cover glass have been studied. Further, Japanese Patent Laying-Open No. 6-45628, for example, proposes application of a resin containing beads mixed therein for scattering light to the surface of the finished solar cell module.
The above described methods, however, involve more complicated manufacturing steps than the general method, when applied to the thin film based solar cell modules, and therefore the cost advantage of the thin film based solar cell modules described above will be lost.
The method of adhering the figured glass as a cover glass increases weight, causes the problem of weather resistance of the adhesive resin for adhesion, and lowers photoelectric conversion characteristic as-the amount of sun light reaching the solar cell decreases. Further, the method of applying resin to the surface of the module causes the problem of weather resistance of the resin.
An object of the present invention is to solve various conventional problems experienced when the unsatisfactory appearance such as glittering as described above is to be prevented, and to provide a thin film based solar cell module of superior appearance free of glittering or the like as well as to provide the method of manufacturing the same in a simple manner at a low cost.
The solar cell module in accordance with the present invention includes a glass substrate having first and second surfaces, and a photo semiconductor device formed on the first surface of the glass substrate, wherein the glass substrate is formed of a figured glass having recesses and protrusions formed to provide antiglare effect on the second surface through which light enters, and the photo semiconductor device is formed of a first electrode layer, a photo semiconductor layer and a second electrode layer stacked successively.
Preferably, the photo semiconductor device may have the first electrode layer, the photo semiconductor layer and the second electrode layer divided into a plurality of areas, the second surface of the glass substrate may have arithmetic mean roughness Ra in the range of 50 xcexcm to 500 xcexcm, and mean distance Sm of the recess and protrusion may be within the range of 0.1 mm to 10 mm.
Preferably, at least one of the first electrode layer, the photo semiconductor layer and the second electrode layer may be divided into the plurality of areas by the step of laser patterning, and the second surface of the glass substrate may be formed to have arithmetic mean roughness Ra of at most 500 xcexcm in that area which corresponds to 100 xcexcm to 5000 xcexcm in the periphery of the portion irradiated with laser in the step of laser patterning.
More preferably, the second surface of the glass substrate may be formed to have arithmetic mean roughness Ra of at most 100 xcexcm in the region corresponding to 100 xcexcm to 5000 xcexcm in the periphery of the portion irradiated with laser in the step of laser patterning.
The method of manufacturing a solar cell module in accordance with the present invention includes the steps of successively stacking a first electrode layer, a photo semiconductor layer and a second electrode layer on a first surface of a glass substrate, and dividing the first electrode layer, the photo semiconductor layer and the second electrode layer into a plurality of areas, wherein at least one of the first electrode layer, the photo semiconductor layer and the second electrode layer is divided into the plurality of areas by the step of laser patterning, the glass substrate is formed of a figured glass having recesses and protrusions for providing antiglare effect formed on a second surface through which light enters, and the method further includes, before the step of laser patterning, the step of placing a transparent material having index of refraction of 1.3 to 1.7 on at least a portion to be irradiated with laser of the second surface of the glass substrate for smoothing the surface to be irradiated with laser.
Preferably, the method may further include the step of removing the transparent material after the step of laser patterning.
Preferably, the index of refraction of the transparent material is 1.45 to 1.55.